Liquid crystal display device and method of fabricating the same

ABSTRACT

A liquid crystal display device includes a plurality of data lines arranged along a first direction on a substrate, a plurality of gate lines arranged a second direction perpendicular to the first direction on the substrate to define a plurality of pixel regions, each of the gate lines having at least one first set of protrusions and depressions, a driving device within each of the pixel regions, a pixel electrode within each of the pixel regions, and a metal layer overlapping each of the gate lines to create a storage capacitor.

The present invention claims the benefits of Korean Patent ApplicationNos. 82698/2002 and 82708/2002 both filed in Korea on Dec. 23, 2002,which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device and a method offabricating a display device, and in particular to a liquid crystaldisplay device and a method of fabricating a liquid crystal displaydevice.

2. Description of the Related Art

In display devices, particularly, in flat panel display devices, such asliquid crystal display devices, active devices, such as a thin filmtransistors (TFTs) are arranged within pixel regions to drive thedisplay device using an active matrix driving method. In the activematrix driving method, the active devices are disposed within each pixelregion and are arranged in a matrix configuration to drive correspondingpixels.

FIG. 1 is a plan view a liquid crystal display device according to therelated art. In FIG. 1, a liquid crystal display device 1 includes anN×M-number of pixels arranged along horizontal and vertical directions,wherein each pixel includes a TFT 10 formed at a cross region of a gateline 3 for receiving a scan signal from an external driving circuit anda data line 5 for receiving an image signal. The TFT 10 includes a gateelectrode 12 connected to the gate line 3, a semiconductor layer 14 onthe gate electrode 12 that is activated by the scan signal supplied tothe gate electrode 12, and a source electrode 16 and a drain electrode17 on the semiconductor layer 14. A pixel electrode 28 is formed withina display portion of the pixel region, and is connected to the drainelectrode 17 to supply the image signal to a liquid crystal materiallayer (not shown). In addition, a storage capacitor metal layer 7 isformed to overlap the gate line 3 and is arranged along the horizontaldirection of the gate line 3 to provide a storage capacitance for theliquid crystal display device 1.

FIG. 2 is a cross sectional view along I-I′ of FIG. 1 according to therelated art. In FIG. 2, the gate electrode 12 of the TFT 10 (in FIG. 1)and the gate line 3 are disposed on a first substrate 20, which is madeof a transparent insulating material, such as glass, and a gateinsulating layer 22 is deposited over an entire surface of the firstsubstrate 20. The semiconductor layer 14 is formed on the gateinsulating layer 22, and the source electrode 16 and the drain electrode17 are formed thereon to form the TFT 10 (in FIG. 1). In addition, thestorage capacitor metal layer 7 is disposed on the gate insulating layer22 so that the gate insulating layer 22 is sandwiched between thestorage capacitor metal layer 7 and the gate line 3 to create thestorage capacitance.

A passivation layer 24 is deposited over an entire surface of the firstsubstrate 20, and the pixel electrode 27, which is made of a transparentelectrode, such as indium tin oxide (ITO), is formed on the passivationlayer 24. In addition, a contact hole 27 is formed in the passivationlayer 24 to electrically interconnect the drain electrode 17 of the TFT10 (in FIG. 1) and the pixel electrode 28.

In FIG. 2, a black matrix 32 and a color filter layer 34 are formed on asecond substrate 30. The black matrix 32 is formed within a portion theTFT 10 (in FIG. 1), and a portion of the black matrix 32 is formedbetween adjacent pixels (i.e., the gate line 3 and regions of the dataline 5) to block light within regions where liquid crystal molecules ofthe liquid crystal material layer 40 are not activated, i.e.,non-display regions. The color filter layer 34 includes red (R), blue(B), and green (G) color filter elements.

In general, the storage capacitance of the liquid crystal display device1 improves sustaining characteristics of the voltage supplied to liquidcrystal material layer 40, thereby stabilizing gray levels and reducingflicker and generation of residual images. Accordingly, storagecapacitance of the liquid crystal display device is considered veryimportant. In FIG. 2, the gate insulating layer 22 is sandwiched betweenoverlapping portions of the gate line 3 and the metal layer 7, therebycreating the storage capacitance. Accordingly, an amount of the storagecapacitance can be controlled by adjusting the area, i.e., width andlength of the metal layer 7, of overlap between the gate line 3 and themetal layer 7.

With the advent of high resolution-liquid crystal display devicesapplicable of displaying high picture quality images, such as the highdefinition TVs (HDTVs), a size of each pixel should be very small.However, the overlap between the metal layer 7 and the gate line 3 islimited so as not to be greater than a set length. Accordingly, theoverlap region of the gate line 3 and the metal layer 7 may be limited.

In order to generate sufficient amounts of the storage capacitance, theoverlap region between the gate line 3 and the metal layer 7 isincreased by increasing the widths of the gate line 3 and the metallayer 7 (since the length of the metal layer 7 is limited).Alternatively, an additional storage capacitance is created by formingtwo storage capacitor metal layers at other regions of a pixel (i.e., acentral region of a pixel) to overlap with the gate line 3 even with thegate insulating layer remaining therebetween. However, increasing thewidth of the gate line 3 or forming the second metal layer reducesaperture ratio.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a liquid crystaldisplay device and method of fabricating a liquid crystal display devicethat substantially obviates one or more of the problems due tolimitations and disadvantages of the related art.

An object of the present invention is to provide a liquid crystaldisplay device that creates a storage capacitance without deterioratingan aperture ratio.

Another object of the present invention is to provide a method offabricating a liquid crystal display device that creates a storagecapacitance without deteriorating an aperture ratio.

Another object of the present invention is to provide a liquid crystaldisplay device having an increased overlap region of a gate line and ametal layer.

Another object of the present invention is to provide a method offabricating a liquid crystal display device having an increased overlapregion of a gate line and a metal layer.

Another object of the present invention to provide a thin filmtransistor having an improved electric mobility.

Another object of the present invention to provide a method offabricating a thin film transistor having an improved electric mobility.

Another object of the present invention is to provide a liquid crystaldisplay device having an improved aperture ratio.

Another object of the present invention is to provide a method offabricating a liquid crystal display device having an improved apertureratio.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, A liquidcrystal display device includes a plurality of data lines arranged alonga first direction on a substrate, a plurality of gate lines arranged asecond direction perpendicular to the first direction on the substrateto define a plurality of pixel regions, each of the gate lines having atleast one first set of protrusions and depressions, a driving devicewithin each of the pixel regions, a pixel electrode within each of thepixel regions, and a metal layer overlapping each of the gate lines tocreate a storage capacitor.

In another aspect, a liquid crystal display device includes a pluralityof data lines and gate lines arranged in a substrate to define aplurality of pixel regions, a thin film transistor within each pixelregion and including a gate electrode on the substrate, a gateinsulating layer on the substrate, a semiconductor layer on the gateinsulating layer and having protrusions and depressions, a sourceelectrode and a drain electrode on the semiconductor layer, apassivation layer on an entire surface of substrate, and a pixelelectrode on the passivation layer.

In another aspect, a method of fabricating a liquid crystal displaydevice includes forming a plurality of data lines arranged along a firstdirection on a substrate, forming a plurality of gate lines arranged asecond direction perpendicular to the first direction on the substrateto define a plurality of pixel regions, each of the gate lines having atleast one first set of protrusions and depressions, forming a drivingdevice within each of the pixel regions, forming a pixel electrodewithin each of the pixel regions, and forming a metal layer overlappingeach of the gate lines to create a storage capacitor.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a plan view of a liquid crystal display device according tothe related art;

FIG. 2 is a cross sectional view along I-I′ of FIG. 1 according to therelated art;

FIG. 3 is a plan view of an exemplary liquid crystal display deviceaccording to the present invention;

FIG. 4A to 4C are enlarged plan and cross sectional views of anexemplary TFT device of FIG. 3 according to the present invention;

FIG. 5 is a cross sectional view along II-II′ of FIG. 3 according to thepresent invention;

FIGS. 6A and 6B are cross sectional views of another exemplary liquidcrystal display device according to the present invention; and

FIGS. 7A and 7B are plan views of another exemplary liquid crystaldisplay device according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

In general, a storage capacitance C may be expressed by: $\begin{matrix}{C = {ɛ \times \frac{S}{d}}} & (1)\end{matrix}$

where ε is a dielectric constant of an insulating layer between twoconductive elements, i.e., a gate line and a storage capacitor metallayer, “d” is a width of the insulating layer, and S is an area of anoverlap region between the gate line and the storage capacitor metallayer.

Accordingly, in Equation 1, increasing the storage capacitance Crequires either an increase in the area of overlap S or a decrease inthe width of the insulating layer “d,” presuming that the dielectricconstant ε of the insulating layer is held constant. In a liquid crystaldisplay device having a constant ε insulating layer of a fixedthickness, the area of overlap S between the gate line and the metallayer must be increased in order increase an amount of the storagecapacitance C. Thus, the area of overlap S may increase withoutincreasing widths of the gate line and the metal layer, or a length ofthe metal layer.

According to the present invention, protrusions and depressions may beformed in the gate line and the metal layer to increase a surface areaof the gate line and the metal layer, thereby increasing the overlapbetween the gate line and the metal layer.. The protrusions anddepressions may first be formed on a substrate, then the gate line andthe metal layer may be formed on the protrusions and depressions.Furthermore, a groove may be formed into a surface of the substrate suchthat the gate line and the metal layer may be formed within the grooveto form the protrusions and depressions.

Since operational characteristics of thin film transistors arerelatively stable, control of the ON/OFF states is easy, and responsetime is fast, the TFTs may be used as active devices of liquid crystaldisplay devices. Electric mobility of the TFTs may be determined by aratio (w/l) of width (w) to length (l) of a channel formed in asemiconductor layer between source and drain electrodes. Accordingly,the length (l) and the width (w) of the channel may be adjusted tochange the electric mobility of the TFT. For example, an intervalbetween the source and drain electrodes may be reduced or the width ofthe semiconductor layer contacting the source and drain electrodes maybe increased. However, it may not be possible to decrease the intervalbetween the source and drain electrodes below a set, standard lengthsuch that the width of the semiconductor layer may be increased toimprove the electric mobility of the TFT. However, if the width of thesemiconductor layer increases, an overall area of the TFT alsoincreases. Accordingly, an aperture ratio of the liquid crystal displaydevice may deteriorate due to an increase of non-display regionsshielded by a black matrix.

FIG. 3 is a plan view of an exemplary liquid crystal display deviceaccording to the present invention. In FIG. 3, a liquid crystal displaydevice may include a pixel region defined by a gate line 103 disposedalong a horizontal direction and a data line 105 disposed along avertical direction, a TFT 110 that includes a gate electrode 112, asemiconductor layer 114 on the gate electrode 112 to be activated by ascan signal supplied to the gate electrode 112, a source electrode 116and a drain electrode 117 on the semiconductor layer 114, and a pixelelectrode 128 formed within the pixel region and electrically connectedto the source electrode 116 and the drain electrodes 117 so that asignal may be supplied to the pixel electrode 128 when the semiconductorlayer 114 is activated.

In addition, the liquid crystal display device may include at leastfirst and second protrusion/depression layers 126 a and 126 b formed ata lower portion of the semiconductor layer 114 and a storage capacitormetal layer 107. The first and second protrusion/depression layers 126 aand 126 b may be arranged along a channel region formed between thesource electrode 116 and the drain electrode 117 when the signal issupplied to the gate electrode 112, and the storage capacitor metallayer 107 may be arranged along the gate line 103. Accordingly, thestorage capacitor metal layer 107 and the gate line 103 may be arrangedalong lower and upper portions of an insulating layer so that thestorage capacitor metal layer 107 and the gate line 103 overlap eachother to create a storage capacitance.

In FIG. 3, at least one third and fourth protrusion/depression layers127 a and 127 b may be arranged along the horizontal direction of thegate line 103. Accordingly, since the third and fourthprotrusion/depression layers 127 a and 127 b may be arranged along thehorizontal direction of the gate line 103 at a lower portion of the gateline 103, the gate line 103 and the metal layer 107 may be formed on thethird and fourth protrusion/depression layers 127 a and 127 b. Thus,protrusions and depressions may be formed in the gate line 103 and themetal layer 107, thereby increasing an area of overlap of the gate line103 and the metal layer 107.

FIG. 4A to 4C are enlarged plan and cross sectional views of anexemplary TFT device of FIG. 3 according to the present invention,wherein FIG. 4A is an enlarged-plan view, FIG. 4B is a cross sectionalview along III-III′ in FIG. 4A, and FIG. 4C is a cross sectional viewalong IV-IV′ of FIG. 4A.

In FIG. 4A, the first and second protrusion/depression layers 126 a and126 b may be arranged along the source electrode 116 and the drainelectrode 117. Specifically, the first and second protrusion/depressionlayers 126 a and 126 b may be formed along the channel between thesource electrode 116 and the drain electrode 117 when the signal issupplied to the gate electrode 112. Accordingly, the surface area of thesemiconductor layer 114 may be increased by the first and secondprotrusion/depression layers 126 a and 126 b, wherein a width of thechannel increases. Since a length of the channel between the sourceelectrode 116 and the drain electrode 117 may remain fixed, electricmobility of the TFT 110 may improve due to the increased width increaseof the channel.

In FIG. 4C, at least first and second protrusion/depression layers 126 aand 126 b may be formed on a first substrate 120, which may includetransparent material(s), such as glass. The first and secondprotrusion/depression layers 126 a and 126 b may be formed by depositinginsulating or metal material(s), then etching the material(s). The gateelectrode 112 may be formed on the first and secondprotrusion/depression layers 126 a and 126 b, and may include a singlematerial layer or a plurality of material layers formed by depositingmetal material(s), such as Al, an Al alloy, and Cu, using evaporation orsputtering methods, and then etching the material(s) with an etchant.Accordingly, corresponding portions of the first and secondprotrusion/depression layers 126 a and 126 b cause protrusions anddepressions to be formed in the gate electrode 112. Thus, the surfacearea of the gate electrode 112 increases than that of the related art.

The gate insulating layer 122 may be deposited on the gate electrode112, and the semiconductor layer 114 may be formed on the gateinsulating layer 122. The semiconductor layer 114 may be formed bydepositing semiconductor material(s), such as a—Si, using a chemicalvapor deposition (CVD) method, and then etching the semiconductormaterial(s) with an etchant. Since the protrusions and depressions areformed in the gate electrode 112 by the first and secondprotrusion/depression layers 126 a and 126 b on the first substrate 120,corresponding protrusions and depressions may also be formed in the gateinsulating layer 122 and the semiconductor layer 114, thereby increasingthe surface area of the gate insulating layer 122 and the semiconductorlayer 114.

As shown in FIG. 4B, the source electrode 116 and the drain electrode117 may be formed on portions of the semiconductor layer 114, and mayboth include a single material layer or a plurality of material layersformed by depositing metal material(s), such as Cr, Mo, Al, an Al alloy,and Cu, using evaporation or sputtering methods, and then etching themetal material(s) with an etchant. Accordingly, protrusions anddepressions may also be formed on the source electrode 116 and the drainelectrode 117 that correspond to the protrusions and depressions formedin the semiconductor layer 114. Thus, the surface area of the sourceelectrode 116 and the drain electrode 117, and particularly the surfacearea contacting the semiconductor layer 114, may be increased.

The passivation layer 124 may be deposited on the first substrate 120including the source electrode 116 and the drain electrode 117, and thepixel electrode 128, which may include transparent material(s), such asITO, may be formed on the passivation layer 124. The pixel electrode 128may electrically contact a portion of the drain electrode 117 of the TFT110 through a contact hole 127 formed on the passivation layer 124.

In addition, the black matrix 132 and the color filter layer 134 may beformed on the second substrate 130 and the common electrode (not shown)may be formed on the color filter layer 134. A liquid crystal materiallayer 140 may be formed between the first and second substrates 120 and130 using a liquid crystal material injection method for injecting theliquid crystal material between the first and second substrates 120 and130 that have been previously attached together. Alternatively, theliquid crystal material layer 140 may be formed using a liquid crystaldispensing method for directly dispensing the liquid crystal materialonto a surface of one of the first substrate 120 and the secondsubstrate 130. Accordingly, uniform distribution of the liquid crystalmaterial across an entire area between the first and second substrates120 and 130 may be accomplished by applying pressure to one, or both ofthe first and second substrates 120 and 130.

FIG. 5 is a cross sectional view along III-III′ of FIG. 3 according tothe present invention. In FIG. 5, the third and fourthprotrusion/depression layers 127 a and 127 b may be formed on the firstsubstrate 120. The third and fourth protrusion/depression layers 127 aand 127 b may be formed by depositing insulating or metal material(s) onthe first substrate 120, and then etching the insulating or metalmaterial(s). The gate line 103 (in FIG. 3) may be formed on the thirdand fourth protrusion/depression layers 127 a and 127 b, and may includeof the same metal material(s) used to form the gate electrode 112 (inFIG. 3) using the same process. Alternatively, as shown in FIG. 3, itmay also be possible to form the gate line 103 using metal material(s)different from the metal material(s) used to from the gate electrode112, and methods used to form the gate line 103 may be different frommethods used to form the gate electrode 112.

The gate insulating layer 122 may be deposited on the gate line 103, andthe storage capacitor metal layer 107 may be formed on the gateinsulating layer 122. The storage capacitor metal layer 107 may includea single material layer or a plurality of material layers formed bydepositing metal material(s), such as Cr, Mo, Al, an Al alloy, and Cu,using evaporation or sputtering methods, and then etching the metalmaterial(s) with an etchant. For example, the storage capacitor metallayer 107 may include the same metal material(s) used to form the sourceand drain electrodes 116 and 117 (in FIG. 3) using a single fabricationprocess. Alternatively, the storage capacitor metal layer 107 mayinclude metal material(s) different from the material(s) used to formthe source and drain electrodes 116 and 117, and the storage capacitormetal layer 107 may be formed using process(es) different from theprocess(es) used to from the source and drain electrodes 116 and 117.

Since the first and second protrusion/depression layers 126 a and 126 b(in FIG. 3) may be formed within the TFT region on the first substrate120, protrusions and depressions may be formed in the layers includingthe gate electrode layer, the gate insulating layer, the semiconductorlayer, and the source and drain electrode layers. Accordingly, thesurface area of each of the layers may be increased. Thus, as shown inFIG. 4C, when the semiconductor layer 114 is activated by a signalsupplied to the gate electrode 112 and the channel is formed along thesurface of the semiconductor layer 114, an overall width of the channelmay be calculated by adding a first width “w1” of the semiconductorlayer 114 without the protrusions and depressions and a second width“w2” due to the increased surface area caused by the protrusions anddepressions. In other words, the overall width of the channel may beincreased by as much the second width “w2,” as compared with the overallwidth of the channel of the liquid crystal display devices according tothe related art.

Since the electric mobility of the TFT is proportional to the width ofthe channel and is inversely proportional to the length of the channel,and the overall width of the channel (w1+w2) is increased, the electricmobility of the TFT is increased because of the protrusions anddepressions. Accordingly, it may be possible to fabricate a liquidcrystal display device having improved operational characteristics whenthe TFT is fabricated having the increased channel width.

In addition, the increased electric mobility of the TFT improves theaperture ratio of the liquid crystal display device. For example, anoverall area of the TFT may be reduced as the overall width of thechannel is increased by the protrusions and depressions. Thus, theaperture ratio of the liquid crystal display device may be increased dueto the reduction of the overall are of the TFT.

Furthermore, the protrusions and depressions may be formed in the gateline 103 due to the third and fourth protrusion/depression layers 127 aand 127 b that are arranged along the gate line 103. Accordingly, thesurface area of the gate line 103 may be increased. Likewise, since theprotrusions and depressions may be formed in the gate line 103, the gateinsulating layer 122, which may be uniformly deposited on the gate line103, may have corresponding protrusions and depressions, and the storagecapacitor metal layer 107 may also have corresponding protrusions anddepressions. Accordingly, the surface area of the storage capacitormetal layer 107 may be increased by the protrusions and depressions. Asa result, the third and fourth protrusion/depression layers 127 a and127 b may increase the surface area of the gate line 103 and the storagecapacitor metal layer 107 that contact the gate insulating layer 122,whereby the area of the overlap region of the gate line 103 and thestorage capacitor metal layer 107 may increase.

The first and second protrusion/depression layers 126 a and 126 b of thefirst substrate 120 may be formed along a horizontal direction betweenthe source and drain electrodes 116 and 117, and the third and fourthprotrusion/depression layers 127 a and 127 b may be formed alonghorizontal direction corresponding to the gate line 103. However, thefirst and second protrusion/depression layers 126 a and 126 b and thethird and fourth protrusion/depression layers 127 a and 127 b may beformed differently. For example, each of the protrusion/depressionlayers 126 a, 126 b, 127 a, and 127 b may include more than twoprotrusions and depressions, and may be formed as a lattice structurehaving a predetermined size. In addition, the protrusion/depressionlayers may be formed in the gate electrode 112 or the gate insulatinglayer 122, not just on the lower substrate 120.

A shape of the protrusion/depression layers may differ. Furthermore, theprotrusions and depressions may be formed on the semiconductor layer 114and the gate insulating layer 122 to increase the surface areas of eachof the different layers, increasing a channel width of the semiconductorlayer 114. Accordingly, it may also be possible to form the protrusionsand depressions by forming groove(s) in a surface of the firstsubstrate.

FIGS. 6A and 6B are cross sectional views of another exemplary liquidcrystal display device according to the present invention. FIG. 6A is across sectional view along IV-IV′ of FIG. 4A, and FIG. 6B is a crosssectional view along II-II′ of FIG. 3. In FIG. 6B, a width of a channeland an overlap region between a gate line 203 and a metal layer 207 maybe increased using a groove formed in a surface of a first substrate220. In FIG. 6A, at least one first set of grooves 226 a and 226 b maybe formed in the surface of the first substrate 220, and a gateelectrode 212 may be formed within the first set of grooves 226 a and226 b. A gate insulating layer 222 may be formed over an entire surfaceof the first substrate 220 including the gate electrode 212, asemiconductor layer 214, and a drain electrode 217 formed on thesemiconductor layer 214.

Accordingly, the semiconductor layer 214 formed on the first substrate220 may include protrusions and depressions due to the first set ofgrooves 226 a and 226 b formed in the surface of the first substrate220. When the signal is supplied to the gate electrode 212, a width ofthe channel along the surface of the semiconductor layer 214 may beincreased to increase the electric mobility of the TFT.

Furthermore, as shown in FIG. 6B, at least one second set of grooves 227a and 227 b may formed in the surface of the first substrate 220, andthe gate line 203 may be formed within the second set of grooves 227 aand 227 b. The gate insulating layer 222 may be deposited on the gateline 203, and a storage capacitor metal layer 207 may be formed on theinsulating layer 222 to create a storage capacitance between the storagecapacitor metal layer 207 and the gate line 203.

The gate line 203 and the gate insulating layer 222 may includecorresponding protrusions and depressions due to the second set ofgrooves 227 a and 227 b formed in surface of the first substrate 220.Accordingly, an overlap region of the gate line 203 and the storagecapacitor metal layer 207 may increase, thereby increasing a storagecapacitance without increasing the width of the storage capacitor metallayer 207.

FIGS. 7A and 7B are plan views of another exemplary liquid crystaldisplay device according to the present invention.

The structures shown in FIGS. 7A and 7B may be similar to those in FIG.3, except for protrusions and depressions formed in the first substrateand structures of a gate line 303 and a storage capacitor metal layer307. In FIG. 7A, at least one second protrusion/depression layer 327 maybe formed in the first substrate to extend along a directioncorresponding to the data line 305. At least one secondprotrusion/depression layer 327 may include a plurality of secondprotrusions/depressions disposed along a direction corresponding to thegate line 303.

In FIG. 7B, a second protrusion/depression layer 327 may be arrangedalong a direction corresponding to the gate line 303. The secondprotrusion/depression layer 327 may include a plurality ofprotrusions/depressions disposed in a lattice configuration and having apredetermined size.

Although not shown in FIGS. 7A and 7B, the protrusion/depression layersmay be formed having different shapes. For example, if the overlapregion between the gate line 303 and the storage capacitor metal layer307 is increased, the protrusions and depressions may be formed havingalmost any shape. In addition, although not shown, the firstprotrusion/depression layer 316 may be formed within the TFT region andmay be formed having various shapes (i.e., a lattice shape), as well asthe second protrusion/depression layer 327.

It will be apparent to those skilled in the art that variousmodifications and variations may be made in the liquid crystal displaydevice and method of fabricating a liquid crystal display device of thepresent invention without departing from the spirit or scope of theinvention. Thus, it is intended that the present invention cover themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

1-19. (canceled)
 20. A liquid crystal display device, comprising: aplurality of data lines and gate lines arranged in a substrate to definea plurality of pixel regions; a thin film transistor within each pixelregion and including a gate electrode on the substrate, a gateinsulating layer on the substrate, a semiconductor layer on the gateinsulating layer and having protrusions and depressions, a sourceelectrode and a drain electrode on the semiconductor layer; apassivation layer on an entire surface of substrate; and a pixelelectrode on the passivation layer.
 21. The device according to claim20, further comprising at least one protrusion/depression layer on thesubstrate to provide protrusions and depressions in the semiconductorlayer.
 22. The device according to claim 21, wherein theprotrusion/depression layer includes insulation material.
 23. The deviceaccording to claim 21, wherein the protrusion/depression layer includesmetal material.
 24. The device according to claim 21, wherein theprotrusion/depression layer is arranged along a direction between thesource electrode and the drain electrode.
 25. The device according toclaim 21, wherein the protrusion/depression layer is arranged having alattice shape.
 26. The device according to claim 20, further comprisingat least one groove formed in a surface of the substrate to provideprotrusions and depressions in the semiconductor layer.
 27. The deviceaccording to claim 26, wherein the groove is formed along a directionbetween the source electrode and the drain electrode.
 28. The deviceaccording to claim 26, wherein the groove is arranged having a latticeshape.
 29. The device according to claim 20, further comprising a metallayer arranged along a direction of the gate line to form a storagecapacitor.
 30. The device according to claim 29, further comprising aprotrusion/depression layer arranged along a direction of the gate line.31. The device according to claim 29, further comprising a groove formedalong a direction of the gate line. 32-50. (canceled)